Conventional barcode scanners detect an optical signal that is reflected off of a distant barcode label. Typically, a laser signal source with a constant amplitude is used to scan the barcode, but the received reflected signal varies as a function of time due to the time varying reflectance along the scanning line. Ambient light from external sources having a constant illumination component and time-varying components masks the weakened reflected signal. Although the constant illumination component can generally be filtered out from the reflected signal, time-varying components too close to the reflected signal frequencies can impede decoding of the reflected signal, thus degrading the performance of the scanner.
Historically, barcode scanners have used retrocollection of the return laser signal to optically track the laser spot on the label. Although this improves the performance of the barcode scanner, there is still ambient light present that is reflected to the detector in these kinds of barcode scanners. Further, laser spot tracking uses oscillating optics that may be expensive to design and implement, particularly for high speed scanners.
There is a need for a system that overcomes the above problems, as well as providing additional benefits. Overall, the above examples of some related systems and associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following Detailed Description.